Metallurgy



Patented May 7, 1946 METALLURGY Arthur Linz, New York, N. Y., assignorto Climax Molybdenum Company, New York, N. Y., a corporatlon of DelawareNo Drawing. Application October 11, 1943, Serial No. 505,842

1 Claim. '(Cl. 75122) The present invention relates to a new, useful andimproved process for the addition of boron to metals and particularly tomolten ferrous metals. I

Objects and advantages of the invention will be set forth in parthereinafter and in part will be obvious herefrom, or may be learned bypractice with the invention, the same being realized and attained bymeans of the. processes, steps and combinations pointed out in theappended claim.

The invention consists in the novel steps, methods, procedures,combinations and improvements herein described.

Heretofore it has been proposed to add boron to molten metals the resultof this addition being additional advantageous properties andparticularly an increase in the hardenability oi the resultventlon,boron is added to a molten mass of metal in the form of a mixture with amolybdenum silicide. r

In my prior Patent No. 2,290,194 I have dis- 0 closed a process forproducing molybdenum sili-' cide for admixture with a molten mass ofmetal and the present invention particularly relates to the formation ofa boron-molybdenum silicide mixture or complex which can be added to amolten metal. By this means not only will the advantages disclosed insaid prior patent be obtained in making a quick solution in the moltenmass-of ant alloy and relatively small quantities of boron have been"effectively utilized for this purpose. As is well known, however, boronis an element characterized by'a high afllnity for oxygen, nitrogen, andoxygen containing gases and therefore one of the difllculties ofintroduction of boron into a molten metal mass has been the oxidizationof part 01 the boron, at least. Furthermore, since only a small quantityoi! boron has been found desirable for such use, another problem isthenecessity or providing rapid and uniform dispersion of the boronthroughout the molten mass. v

In the prior proposals the boron has been introduced into the moltenmass for example in the form of term-boron or as an admixture with othermetals such as aluminum, calcium, titanium and term-silicon.

The object of the present invention is to pro-.

. vide a novel and improved process for 'the addition of boron intomolten metal such as iron or steel while preventing oxidization of theboron;

A further object of the invention is to provide for incorporating boroninto molten iron or steel or like metals while obtaining a rapiddispersion throughout the molten mass of the boron, thus reducing theopportunity for oxidization of the boron. Itis also an object ofthepresent invention .to provide a novel and improved process by which adefinite ratio of boron can be accurately added tothe molten metals suchas iron or steel.

The invention further provides the process of producingalboron-containing compound which is adapted to .be added to a moltenbath of metal molybdenum and silicon, but also. the boron carried by themolybdenum silicide will be dispersed quickly in the molten mass anddissolved therein without substantial exposure'to .oxidization by virtueof this fact and also by virtue of the fact that the silicon in thesilicide will help prevent oxidization of the boron.

Various processes may be used for the preparation of themolybdenum-silicon-boron' addition agent which may be used in thealloying process oi! the present invention. I preferably mix amolybdenum oxide such as roasted molybdenite concentrates or puremolybdenum trioxide with ferro-silicon and a fluxing agent such asfluorspar, with aluminum, together with either boric acid, sodium tetraborate, or other compound forming a source of boron. This mixture is'then ignited in a suitable crucible and after the slag has been tappedof! the desired proportion of molybdenum and silicon, together withboron is present in the form of a molybdenum-siliconpending upon thedesired composition of the resultant product and particularly how muchboron is to be introduced into the final alloy.

It is desired, preferably, to produce a final addition product whichwill be molybdenum silicide containing from 1% to 1% to 2.50% of boron.A

I typical analysis of the addition product produced to provide ready andrapid dispersion of the boron therethrough while avoiding losses byoxidization.

According to the process of the present inby the reaction of such amixture is:

' Per cent Mo Si 30 B 1.5 A1 .2 AlzOa- 4.7 09.0 1.5 $102 2.1

If desired an excess of silicon may be added to the mixture so as tointroduce a larger proportion of silicon into the final alloy and alsopresent an adequate surplus of silicon for the prevention of oxidizationof the boron.

After the mixture has been ignited and the slag tapped off, theresultant mass of molybdenum silicide plus boron can be crushed to formsmaller lumps which can be weighed out into convenient amounts foraddition to the molten metal in any desired manner.

In use the molybdenum silicide boron complex is employed insubstantially the same manner as is customary with ferro-alloys wherebythe addition agent is added directly to the molten material as forinstance in the ladle, although the molybdenum silicide boron complexhas a different range of usefulness from that of ferro-molybdenum due toits exothermic nature and by reason of the fact that there isaccomplished the simultaneous addition of molybdenum silicon andboronwith a rapid dispersion of the boron through the mix. Theseproperties combine to make the process of the present invention su-'hereinbefore-mentioned specific example, then the amount of the complexwhich is added to the molten batch will be such as to include 10 pointsof molybdenum in the final cast alloy which will result in the castalloy containing .0025% of bo- -ron. Other compositions of themolybdenum silicide boron complex addition agent may be obtained byvarying thev quantity of the boron and of the molybdenum and silicon inthe reaction mixture in order to obtain the desired amount of all threeof these materials in the final cast alloy.

It is thus obvious that the present invention provides a distinctadvantageous process in that not only is the quantity of molybdenum andsilicon controllable with respect to the final alloy but also thequantity of boron can be controlled to suit the desired result.

If desired, the molybdenum silicide boron complex may be added with theother ingredients of a ferrous alloy prior to introduction into a, blastfurnace or electric furnace and in this case the molybdenum silicide'boron complex is dissolved in the ferrous material as this is melted,the silicon thus generated being capable of preventing the oxidizationof the boron so that the boron will ultimately be dispersed through themolten mass. Alternatively, the molybdenum silicide boron complex may beused to replace a portion of the now commonly used ferro-molybdenumwhereby a smaller proportion of silicon will be obtained in the finalalloy and the advantages of the boron will result in a final alloy withincreased properties such as hardenability.

While the process of this invention has been described principally inconnection with the-production of ferrous alloys having a molybdenum andsilicon content to which it is desired to add boron, the process mayalso be applied to the production of non-ferrous alloys such as aluminumand magnesium alloys where it is desired to introduce a, small quantityof boron into the alloy.

The invention i'n its broader aspects is not limited to the specificsteps and procedures described but departures may be made therefromwithin the scope of the accompanying claim without departing from theprinciples of the invention and lybdenum silicide complex containingapproximately molybdenum} approximately 30% silicon, approximately 1.5%boron, and the remainder impurities, the addition being made at atemperature suflicient to dissolve the boroncontaining complex inthe'molten metal.

ARTHUR .LINZ.

